In Vitro Studies of Lipopolysaccharide-Mediated DNA Release of Podovirus HK620
In Vitro Studies of Lipopolysaccharide-Mediated DNA Release of Podovirus HK620
复制标题
DOI：
10.3390/v10060289
复制
发表时间：
2018-06-01
期刊：
影响因子：
4.7
通讯作者：
Barbirz, Stefanie
中科院分区：
文献类型：
--
作者：
Broeker, Nina K.;Kiele, Franziska;Barbirz, Stefanie
革兰氏阴性菌通过一层含有脂多糖（LPS）的最外层来保护自身。O抗原特异性噬菌体利用尾刺蛋白（TSP）来识别并切割LPS的O - 多糖部分。然而，O抗原的组成和结构会根据环境条件而有很大差异。了解这些变化如何影响噬菌体感染周期的早期阶段是很重要的，因为它们可能与宿主范围的改变或噬菌体抗性的产生有关。在这项工作中，我们分析了体外制备的LPS如何触发大肠杆菌短尾噬菌体HK620的颗粒打开和DNA释放。基于荧光的DNA释放监测表明，体外的HK620噬菌体颗粒以与其他短尾噬菌体相当的速度释放其基因组。此外，我们发现HK620在限制低温下通过其TSP不可逆地吸附到LPS受体上，但不打开颗粒，而在适宜温度下能够释放其DNA。DNA释放仅由LPS刺激，然而，O抗原的组成决定了LPS受体是否能够在体外启动大肠杆菌噬菌体HK620的DNA释放。这一发现对于优化用于治疗的噬菌体混合物可能具有重要意义，因为在自然环境中O抗原结构可能会迅速变化。
Gram-negative bacteria protect themselves with an outermost layer containing lipopolysaccharide (LPS). O-antigen-specific bacteriophages use tailspike proteins (TSP) to recognize and cleave the O-polysaccharide part of LPS. However, O-antigen composition and structure can be highly variable depending on the environmental conditions. It is important to understand how these changes may influence the early steps of the bacteriophage infection cycle because they can be linked to changes in host range or the occurrence of phage resistance. In this work, we have analyzed how LPS preparations in vitro trigger particle opening and DNA ejection from the E. coli podovirus HK620. Fluorescence-based monitoring of DNA release showed that HK620 phage particles in vitro ejected their genome at velocities comparable to those found for other podoviruses. Moreover, we found that HK620 irreversibly adsorbed to the LPS receptor via its TSP at restrictive low temperatures, without opening the particle but could eject its DNA at permissive temperatures. DNA ejection was solely stimulated by LPS, however, the composition of the O-antigen dictated whether the LPS receptor could start the DNA release from E. coli phage HK620 in vitro. This finding can be significant when optimizing bacteriophage mixtures for therapy, where in natural environments O-antigen structures may rapidly change.